A color filter is the most costly component in key components of an LCD, and occupies about 20% of all material costs in the material cost composition of a Thin Film Transistor Liquid Crystal Display (TFT-LCD) panel.
The color filter is used to generate RGB (Red, Green, Blue) colors through light filtering. Then, RGB colors are mixed in different proportions to generate various colors, such that the LCD can display in colors. Meanwhile, the color filter also plays a pivotal role for the width of the visual angle, luminance, resolution and the like of the TFT-LCD.
For instance, as for a fifth produced TFT-LCD, the material cost of its components is 70% of its total cost. The cost of the color filter is approximately 18.9% of the total cost. Calculated by the material cost alone, the cost of the color filter is up to 27%.
The materials for the color filter comprise glass substrate, color photoresist, ITO, Cr target for black frame, and so on. And the material cost occupies 60%-70% of the total cost of the color filter, whereby glass is the greatest item of the material cost of the color filter, which is approximately 40%. If the material cost contains the cost of the black frame, then the cost of glass exceeds 50%. The next one is the photoresist, which is 27%.
There are three fundamental colors, which are red, green, and blue separately. These three colors are not only main colored light obtained from the decomposition of white light, but also principle components of the mixed colored light, and additionally match spectral response range of human eye retina cell to meet the physiological effects of color vision of human eyes. Three kinds of colors mixed in different proportion can generate almost all colors in nature, with the greatest color gamut. Meanwhile, three kinds of colors are independent among one another, that is, one of the primary colors is unable to be generated by mixing other colors. Thus, Red (R), Green (G), and Blue (B) are named as three-primary colors of the colored light.
A subtractive color method is an approach for reproducing a color by subtracting the primary color(s) from the white light. Generally, the subtractive color method can be deemed as an approach for obtaining a color by overlapping three complementary colors that are cyan, magenta, and yellow. Each color is obtained by subtracting its complementary color from the white color.
An additive color method is an approach for generating, by adding RGB primary colors in different proportion, other colors.
The color LCD usually mixes colors using the additive color method.
The liquid crystals per se can only present black-and-white images. For colorful display, it is necessary to dispose color filters of RGB colors on a liquid crystal panel. In a thin film transistor (TFT) active matrix driven display, parallel electrodes are sequentially disposed into the color filters of RGB colors. Due to the problem of the mixed partial-color, a black matrix can be disposed among color coatings with different colors. The manufacturing quality of the black matrix would influence on the image resolution and color definition of the ultimate display image.
The RGB diaphragms of traditional color filters are arranged as illustrated in FIG. 1. Namely, in a plurality of columns of diaphragms, diaphragms are arranged in terms of Red diaphragm, Green diaphragm and Blue diaphragm.
However, as illustrated in FIG. 2, in a mixed color image, when signals sent to pixels through data lines are switched between a high voltage and a low voltage, a waveform for the inputted pixel data is better than the previous one due to RC delay. Therefore, the voltage charged into pixels later is higher, and thus the LCD will be brighter and one of the colors will be highlighted. There is an obvious color cast when the RC delay on both sides of the liquid crystal panel widely differs from the RC delay in the middle of the panel.
A pixel driven module of a display has been disclosed in CN 1549240A, wherein sub-pixels of RGB light are selected separately to form a pixel structure. One or two sub-pixels from the pixel device can be selected to widen, and the widened sub-pixels can be shared with an adjacent pixel structure so as to reduce the amount of sub-pixels, improve the acceptability and increase the resolution of the display. It, however, does not solve the above-mentioned problem as to color cast.
Therefore, during the procedure of designing the panel of the TFT-LCD, it is an important problem for designers to avoid the color cast. The external manifestation of the color cast is that colors in a mixed color image are distributed unevenly, whereby a kind of color will be highlighted. For example, a yellow image may appear in a shade of red. The color cast decreasing the display quality of the panel seriously must be solved. Accordingly, the present disclosure provides a color filter and a corresponding LCD, which can tactfully solve the problem of the color cast based on the principle of the color cast.